Bell Work: 12/3/14
–Number your bell work
–On your bell work sheet,
write down the words
that match the
EQ & Objectives
•Identify the unique
ridge patterns of a
prints from a crime
scene and identify
Latent Print Challenge
Do the substances on people’s
hands affect latent prints left
Challenge: Your challenge is to
design an experiment to see how
substances on people’s hands,
such as lotion, soap, and hand
sanitizer, affect the quality of
latent prints left on paper.
• (People) Purpose
– State the problem
• (Really) Research
– Find out about the topic
• (Hate) Hypothesis
– Predict the outcome of the problem
• (Eating) Experiment
– Plan a procedure to test the hypothesis &
test your hypothesis
• (Dark) Data
– Record the results of the experiment
• (Chocolate) Conclusion
– Compare the hypothesis to the experiment
Complete the first three steps of the Scientific
Method in your STEM notebook:
Write the purpose of the experiment (refer back to the latent
print challenge page).
2. Complete research on the following topics:
− Latent prints
− Amino Acids
• Answer the following question: What could be researched in
order to find out what substances on human hands could react
with Ninhydrin, developing a better quality print?
• Decide what substances you want to use in your experiment.
Think about common substances humans put on their hands.
For example, you could use lotion.
3. Form a hypothesis: What substance on human hands will
develop the best quality print?
What you should have figured
out from your research…
1. Latent prints are invisible prints that have to
be developed by powders, special lights, or
2. Ninhydrin is a chemical or solution that reacts
with amines or amino acids from our skin
(sweat and oils, which contain proteins) to turn
the latent print purple.
3. We need to see what common substances
that we put on our hands contain amines that
could better react with the Ninhydrin to
develop a better quality print.
List of ingredients
Are any of these amines?
You must meet the following standards
tomorrow during the experiment:
1. You must wear closed toe shoes
(NO sandals or flip flops!)
2. If you have long hair, you must
have it pulled back!
3. You must wear pants or skirts that
reach the ankle (NO capris, shorts,
or mini-skirts!) and a long sleeve
Tweet a response…
What is your hypothesis?
Predict which of your
substances will have the
greatest effect on the quality
of latent prints.